Theaetetus

​SOCRATES: Therefore, since these things must move, and not moving cannot belong to anything, all things must always be moving in every kind of motion. THEODORUS: Necessarily so. SOCRATES: Consider, then, this point of theirs for me: did we not say they assert that the generation of heat or whiteness or anything whatever occurs in this way, namely, that each of these is carried along together with a perception between the active and the passive elements, and the passive element becomes percipient but not a perception, while the active element becomes of a certain quality but not a quality? Perhaps, then, “quality” appears to you to be a strange word, and you do not understand it when spoken of all at once; so listen to it in parts. For the active element does not become heat or whiteness, but hot and white, and so with the rest. For you surely remember that in the foregoing discussion we said in this way, that nothing is one itself by itself, nor indeed the active or the passive element, but from both of them coming together with one another, generating perceptions and perceptible things, some become of certain qualities, and others become percipient. THEODORUS: I do remember; how could I not? SOCRATES: Let us then let the other matters go, whether they say them in this way or otherwise; let us keep only to that for the sake of which we are speaking, by asking: “Are all things moving and flowing, as you say? Is it so?” THEODORUS: Yes. SOCRATES: Surely, then, they are moving in both ways that we distinguished, both being carried along and altered? THEODORUS: How could they not, if indeed they are to move completely? SOCRATES: If then they were only carried along, but not altered, we would surely be able to say of what sort the things carried along are flowing; or how do we say it? THEODORUS: In this way. SOCRATES: But since not even this remains constant, that the flowing white flows as white, but it changes, so that there is a flow of this very thing, whiteness, and a change into another color, lest it be caught remaining in this state, is it ever possible to designate any color, so as to address it correctly? THEODORUS: And what way is there, Socrates? Or any other of such things, if indeed it always slips away from the speaker, inasmuch as it is flowing? SOCRATES: And what shall we say about any perception whatsoever, such as that of seeing or hearing? Does it ever remain constant in seeing or hearing itself? THEODORUS: It certainly must not, if indeed all things are moving. SOCRATES: Therefore, we must not call something seeing any more than not seeing, nor indeed any other perception any more than not, since all things are moving in every way. THEODORUS: Indeed not. SOCRATES: And yet perception is knowledge, as I and Theaetetus said. THEODORUS: That was so. SOCRATES: Therefore, when asked what knowledge is, we answered with something that is no more knowledge than not knowledge.

THEODORUS: It seems so. SOCRATES: Fine indeed would be the correction of our answer, when we were eager to demonstrate that all things are moving, so that that answer might appear correct. But, as it seems, it has appeared that, if all things are moving, every answer, about whatever one may answer, is equally correct—to say that it is thus and not thus, or, if you prefer, that it becomes, so that we may not make them stand still by our language. THEODORUS: You speak correctly. SOCRATES: Except, Theodorus, that I said both “thus” and “not thus.” But we must not even say this word “thus”—for ”thus” would no longer be moving—nor again “not thus”—for this is not motion either. But some other language must be established for those who speak this doctrine, since as it is now, they have no words for their own hypothesis, unless indeed “not even thus” would fit them best, being spoken without limit. THEODORUS: This is indeed the most appropriate dialect for them. SOCRATES: Therefore, Theodorus, we are rid of your companion, and we do not yet concede to him that every man is the measure of all things, unless he is a prudent person; nor shall we concede that perception is knowledge, at least according to the method of all things moving, unless indeed this Theaetetus here says otherwise. THEODORUS: You have spoken best, Socrates; for these things being concluded, I too ought to be rid of answering you according to our agreement, since the discussion concerning the doctrine of Protagoras has reached its end. THEAETETUS: Not, indeed, before, Theodorus, you and Socrates go through those who on the contrary assert that the whole stands still, just as you proposed just now. THEODORUS: Being young, Theaetetus, do you teach your elders to do injustice by violating agreements? But prepare yourself so that you may give an account to Socrates of the remaining matters. THEAETETUS: If indeed he wishes. I would, however, have most gladly heard about the things I am speaking of. THEODORUS: You challenge Socrates “cavalry into the plain” in challenging him to discussions; ask, then, and you shall hear. SOCRATES: But I think, Theodorus, that concerning the things Theaetetus commands, I shall not obey him. THEODORUS: Why indeed will you not obey?